Re: [PATCH v3 2/2] dt-bindings: rtc: m41t80: Mark the clock: subnode as deprecated

[Marek Vasut <marex@denx.de>]

On 12/16/22 15:24, Sebastian Reichel wrote:
> Hi,

Hi,

> On Thu, Dec 15, 2022 at 08:39:47PM +0100, Marek Vasut wrote:
>> On 12/15/22 19:06, Sebastian Reichel wrote:
>>> On Sun, Dec 11, 2022 at 09:51:24PM +0100, Marek Vasut wrote:
>>>> The clock {} subnode seems like it is describing an always-on clock
>>>> generated by the PMIC. This should rather be modeled by consumer of
>>>> the clock taking phandle to the RTC node itself, since it already
>>>> does have clock-cells and all. Since there are no users of the clock
>>>> subnode in tree anyway, mark it as deprecated to avoid proliferation
>>>> of this approach.
>>>>
>>>> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Signed-off-by: Marek Vasut <marex@denx.de>
>>>> ---
>>>> Cc: Alessandro Zummo <a.zummo@towertech.it>
>>>> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
>>>> Cc: Rob Herring <robh+dt@kernel.org>
>>>> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
>>>> Cc: linux-rtc@vger.kernel.org
>>>> To: devicetree@vger.kernel.org
>>>> ---
>>>> V2: - Add AB from Krzysztof
>>>> V3: - No change
>>>> ---
>>>
>>> I just noticed this by accident. Basically everything in the patch
>>> description is wrong:
>>>
>>> 1. There is a in-tree user: arch/arm/boot/dts/imx6dl-qmx6.dtsi
>>
>> Sorry, I missed this one.
>>
>>> 2. The PMIC has nothing to do with this
>>
>> In [3] the commit message claims the PMIC supplies 32kHz clock to i.MX6 CKIL,
>> which per IMX6DQRM rev.6 Table 18-3 row SNVS indirectly supplies SNVS RTC.
>> This reminded me of commit:
> 
> The word PMIC is not mentioned once in [3].

s@PMIC@m41t62 RTC@, sorry.

> PMIC is not involved.
> The QMX6 32khz chain is like this:
> 
> 32kHz crystal -> m41t62 crystal input
> m41t62 clock output -> i.MX6 CKIL
> 
>> 9509593f327ac ("arm64: dts: imx8mm: Model PMIC to SNVS RTC clock path on
>> Data Modul i.MX8M Mini eDM SBC")
>>
>> which solves exactly the same problem, system hangs when 32 kHz clock are
>> stopped, except this time on i.MX8MM, clock are generated by PMIC on I2C
>> (notice how the PMIC is referenced directly) and the clock are supplied to
>> the SVNS RTC XTal terminals.
>>
>> I wonder if this could be reused on the QMX6 board too?
> 
> IIRC On i.MX6 referencing the I2C connected RTC results in boot
> hanging forever when trying to get the ckil clock in
> imx6q_clocks_init. At least it used to be the case when I was
> working on this - I no longer have access to the boards. Of course
> properly referencing the RTC clock was the first route I tried.

Hmmmmm, what shall we do, un-deprecate the clock sub-node ?